Evolution and humans: big brain size uses energy (Evolution)

DAVID: The fossils demonstrate loss of muscle while the brains are still small and they are bipedal. There is an obvious sequence. Environmental response does not affect the sequence I point out.

dhw: I can’t comment on this until you explain to me what muscles early hominins actually lost and when they lost them. If you’re thinking of 23 million years ago, it may well be that the adjustment did not require any development of the brain. Clearly your God didn't think it did, since you're telling us he did NOT expand their brain before they descended!

DAVID: A study on Lucy decided she probably was a partial tree dweller who fell to her death, but it was her slight build that originally hid that conclusion from earlier studies. Earlier hominins had smaller upper bodies than apes, while their brains were still small implying they left tree dwelling and then grew larger brains in that sequence.

dhw: If I’ve understood you correctly, then, the sequence supports my hypothesis that once they left the trees, there were new tasks to be performed, as a result of which their brains expanded.

I know brains expanded in jumps with each new species in the advance of hominins to humans, and your approach does not fit the facts of brains becomimg smaller among humans with increased use.